


Unplanned

by Antartique



Category: Katekyou Hitman Reborn!, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia
Genre: Alternate Universe - Reincarnation, Deku and Kacchan are BFFs, Gen, self-indulgent nonsense
Language: English
Status: Completed
Published: 2020-11-08
Updated: 2020-11-08
Packaged: 2021-03-09 02:06:59
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 3,658
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27446854
Author URL: https://archiveofourown.org/users/Antartique/pseuds/Antartique
Summary: When Bakugō Katsuki and another student get kidnapped, Midoriya Izuku knows he is going to die getting them back— Sadly, he will probably be killed by his own best friend’s brother before the Villains can get to him.[Or, Bakugō Hayato, maybe Vigilante, is having a very bad day.]
Relationships: Bakugou Katsuki & Gokudera Hayato, Bakugou Katsuki & Midoriya Izuku
Comments: 10
Kudos: 196





	Unplanned

**Author's Note:**

> **Warning:** Not really _graphic_ , but someone has an overactive imagination.
> 
> I was supposed to be working on ‘corrupt the sky’, but then I saw Dabi’s chapter and just. He’s so dramatic. I love him. So, a whole ‘verse was built, and some scenes written, and this just happened to be the most coherent one. I know Bakugō Hayato is overdone, but I find it hilarious; this was titled ‘hayato’s unplanned vigilantism while trying to fix the mess of an underworld in the hero era’.
> 
> I’m borrowing some elements from ‘corrupt the sky’, mostly these:  
>  **1.** Namimori is secret flame society and also autonomous of Japan thanks to a certain Cloud’s meddling. Everyone is somehow related, because it has a really regulated entrance.  
>  **2.** The Vongola 10th Generation has the most advanced technology ever created. Hayato also decided to play real life Battleship in the future, because if you have the technology for it, why not?  
>  **3.** Everyone has flames, usually as direct opposite pairs so they can’t really be used; they are a natural part of humanity. Those who _can_ use them have either more than two, one overpowers the other, or they happen to be complementary.
> 
> Let me know if you are interested in me sharing more!

Izuku is going to get killed.

No, not just killed. First murdered, then dismembered; maybe he will be dismembered before he is murdered. He will be put in a trash bag, or multiple trash bags, and thrown away in the river, his body will never be found. Or, it might be found, but he will be long dead, probably after drowning with weights attached to his legs.

It will be messy. His mother will cry, but only for a bit, because she will go along with the murder; his father in his eternal absence might join in as well. Mitsuki-san and Masaru-san will probably watch as Katsuki kills Izuku, either slow or quick, but no one will do anything about it. No one will ever know, Midoriya Izuki will disappear from the records afterwards, just a void memory, an empty room, a name that never made a single wrinkle in history.

He is going to get murdered. It will be messy. It will be Katsuki, and no one will tell on him: everyone will be an accomplice, and it will not matter, because—

“Bakugō?”

Iida is looking at Bakugō, because that is who it is. There is the reason for Izuku's future demise: simply there, existing, perched on a wall, a crossbow loaded with a crystal-tip arrow leaning at his side, silver blond hair tied back with a red ribbon. A box of who-knows-what is by his feet, along with a bag filled with, if Izuku remembers right, _civilian-grade_ _firecrackers_ and a _legally acquired, non-lethal_ airgun. All perfectly safe and within bounds of what a normal high-schooler can acquire, because one thing _this_ Bakugō is most definitely _not_ , is Hero candidate.

[ _‘All bought properly with my own money— I have been doing odd jobs. It is cash, father, it is fine, the purchases won’t be linked back to you—‘_

 _‘That is_ not _the problem here! It is a_ gun _, where do you think— How did you even find this? Was it Hisashi, I will talk to him—‘_

_‘Huh. I thought the crackers might be the issue, not the—‘_

Izuku looks at Katsuki. Katsuki looks at Izuku. Mitsuki continues trying not to laugh. The three of them make the wise decision to get out of the room, carrying the kilograms of pyrotechnic material and the hobby weaponry that were somehow acquired and delivered without anyone noticing.]

The boy is dressed in all black and his eyes are hidden behind red-tinted goggles. What a nostalgic sight, Izuku is going to get killed.

“Bakugō, how did you get _out—_ “

But, this isn’t the Bakugō they are looking for, not the Bakugō they are rescuing. Bakugō Katsuki is still held inside the building, one of the targets of a kidnapping, and of their rescue. The one standing in front of them, all decked out for battle, _is not_ their classmate. He is the reason for Katsuki’s safety, the reason for Katsuki’s _everything_ —and also for Izuku’s future, well-deserved death.

Bakugō Hayato raises his goggles, and it becomes even more obvious this is _not_ Katsuki, but rather a motive for murder. Izuku feels himself go cold at the sight of the dark eyebags around his eyes, tiny crystals forming on his fingertips, of the small twitch of his limbs. It is but a tiny shiver of anticipation and stored energy, ready to be let out.

A ticking bomb.

Forget Katsuki. _Hayato_ will end up murdering them if they don’t do something soon. Izuku isn’t sure if Katsuki told Hayato about their classmates, or about their class at all: for all they share most of everything, Katsuki and Hayato like to pretend they don’t really care about each other's chosen paths. Classmates are too unimportant in the grand scale of things, especially when there are other things to worry about—

[ _‘I'm going to be a Hero, I can’t have something holding me back. You do that enough, Deku. I’m serious, let him forget himself as he wastes away in the library.’_

_‘I don’t care. You two want to be heroes and kill yourselves, go ahead. I just want to live my life in peace. Don’t come crying to me when you make a mistake.’_

They both spoke with such forced bitterness, Izuku never believed a word they said. He watched in silence as Hayato’s stalkers stopped showing up, as Katsuki’s injuries were bandaged each time he knocked himself out. He watched how they trained, how they burned themselves out, so similar yet so different.

He watched, and never mentioned it. Never mentioned how Katsuki combed through Hayato’s research notes, or how Hayato kept _casual_ correspondence with Katsuki’s assigned support student.

He might have made a mistake.]

Green eyes bore into their souls, photographic memory and genius mind working overtime to recognize them; he probably saw them in the Sports Festival. His eyes narrow, almost glowing scarlet, and Izuku is reminded of one of many encrypted files in his and Katsuki’s phones, delivered after Stein and the Swordmaster’s attack:

> _toga h., q:transform, w:blade melee, mo:just steal identities, it’s fine, i’m a vampire now._

Hayato signs a simple, subtle greeting to Izuku, and Izuku signs the right response back —his brain is panicking at the idea, but this is one ritual he has memorized and practiced, part of childhood games and maybe something else—

[‘ _In case there is ever an impostor amongst us, this will be our signal,_ ’ Hayato said with all the seriousness he ever had, which is a lot; the effect is ruined by how he is lounging on the bed, head upside down and wearing kitty-print pajamas. The blanket barely covers them anymore: they are nine, and Izuku loves them, but the twins are stupid and always refuse his gifts, so the oversized blanket they _could_ use is acting as a fort downstairs.

The three of them are the same, right now. They are watching some colorful cartoon, upside down, while waiting for their parents to stop fighting downstairs. Something about experiments with explosives without supervision, even though Izuku was supervising —no, it is about _adult_ supervision, Izuku, you can’t just experiment with their Quirks without protection! I don’t _care_ it is an abandoned building, Hisashi, speak to your son, stop _laughing!_ Masaru, act as the common sense these two lack, _please_ —

It has been going for a while.

‘ _When did you learn sign?’_ Katsuki asks, almost nonchalant, but he repeats the motion. Hayato corrects his sign, because it has to be _perfect_ , they will use it as their code word for infiltration after all. Izuku repeats the motion as well, and Hayato corrects him too. It takes a few repeats, and many months, for the motion to come out right, and by then it is just another odd quirk of the childhood friends.

‘ _It’s not sign, it’s flarespeech. It hasn’t been in use in decades, so it should be safe—‘_ ]

—but now it is a reassuring sight. This is Bakugō Hayato, whose information is always accurate, whose notes on Quirks might be more detailed than Izuku’s own. He probably has a whole file on their classmates and on One for All, and maybe Izuku should be worried, but Hayato has always inspired trust.

Well, most of the time. Now he just looks like a terrorist.

“Hayato, not Katsuki,” he finally says, putting the goggles back in place. The crossbow stays where it is. He is waiting, then; for what? “They aren’t in position yet, if you’re wondering.”

“ _Hayato?_ ” Kirishima is obviously confused, so Katsuki didn’t tell him about Hayato at all. If he didn’t tell Kirishima, then he didn’t tell anyone; Hayato’s identity is still a mystery.

“ _They_?” Yaoyorozu pulls out some binoculars and looks at the building. She makes an undignified noise, quickly dropping behind the wall and pulling Kirishima with her. “The _Heroes..._ “

Kirishima trips. Izuku follows. They end up in a curious hole in the ground and a messy tangle of limbs, protected by a wall that might have been a building once, with the wrong Bakugō looking down at them in amusement. He hops down as well, leaving his weapons atop the broken wall, and hovers besides Iida once they are out of the pitfall trap for a hurried introduction.

“Bakugō Hayato, Kacchan’s younger twin,” Izuku then motions to everyone else. “Class 1-A, Yaoyorozu, Iida, Todoroki, Kirishima. Myself. Why—“

“Mist, Sonic, AC, Baby Shark. Deku.” Oh, God, those are _not_ Katsuki’s nicknames, he has been gossiping. The anxious tremble comes back with fury and Hayato tugs at his sleeves. “I thought you were under hospital arrest, _o qualcosa_. Breaking the rules, are we.”

A dangerous line of thought, that is. The others look guilty, a little sick, angry —and then there is Todoroki, who just looks at Hayato like he is an evil clone. Maybe he _does_ think that: twin of a classmate who never talks about himself, wears all black, shows up unannounced at the _right_ _moment_ with barely legal weaponry. An evil clone, a vigilante, maybe even a villain; Hayato has never been good at playing civilian.

It _is_ weird, though, because—

“ _Please_ don’t say you were planning on going there alone.” Kirishima is quick to adapt to Hayato, just as he is quick to adapt to Katsuki. He sounds accusing and oddly resigned, just like when he is trying to talk Katsuki out of his more dangerous strategies and training. So similar, yet so different.

“I’m more surprised you are _waiting_.” Izuku looks up at Hayato, and Hayato looks down at Izuku. Patience is _not_ a Bakugō’s virtue, even less so _Hayato_ ’s virtue.

[ _‘NOT AGAIN!’_

Izuku rarely hears Hayato yell. Being loud is more Katsuki’s thing, ever since they were children. Katsuki, who would run and laugh, the king of the playground and a ray of sunshine; and Izuku, who chased after him on clumsy feet with excitement and endless rambles. Katsuki was the loud one, while Izuku _used_ to be loud along with him. Hayato prefered the quiet rustle of a tree, climbing higher than anyone else so he could read and read and _read_ , rarely letting his own curiosity shine in front of others.

That was outside, and also, years ago. Nowadays, Katsuki is explosive in more ways than one, with a hair-trigger temper and proud declarations, only calming down when inside four walls. Izuku prefers to ramble to himself or to his notebooks, keeping his enthusiasm and words to his loved ones. Hayato… he is a night owl, dazed through the day while his brother drags him around, coming to life when the sun sleeps so he can do his UMA-spotting.

Which is why, when one of the top students of Aldera Junior High (Izuku, Katsuki and Hayato swap first to third places for their theory classes every exam season, though Izuku has advantage in socials, Katsuki in sciences and Hayato in languages; practical classes aren’t counted in their scorekeeping) yells, screams and almost throws the computer he was using out the window, people flee. Bakugō Hayato losing his immovable composure means one thing, and one thing only, and they are in a highly flammable computer room.

Lucky for them, the explosions don’t start right away. Hayato drops his head on the desk, hiding his face in his arms, while Katsuki (who is definitely _not_ the neutralizing half of the chemistry duo) pats his arm. The elder twin is frowning at the screen as if it personally offended him, and knowing Katsuki, it probably did.

Izuku goes to see what the commotion is about and, sure enough, the screen was highly offensive: _uri.djvu_ was running on the system, laughing at them like always. Removing it wasn’t _hard_ , not to Hayato at least, but this is the fifth time in the month, and they are not even half way through.

 _‘Maybe wait for your own computer to get here?’_ Izuku doesn’t know how long it takes to build a computer, especially not the one with the specs Hayato needs. It was ordered last week, after a whole year of _uri.djvu_ deciding to nap on the school’s computers like it belonged there. They are all very lucky the teachers don’t bother with computer class: the computer room is free-for-all two hours a week.

 _‘Can’t wait— My_ research!’ Hayato practically wails, curling up on Katsuki’s side like when they were children, little deadly crystals forming where their skins meet. Izuku takes a step back. Then another.

 _‘Three days, Hayato. Three days, is all I ask.’_ Katsuki’s defeated voice is but an echo of many, many times he asked for the same three days. _uri.djvu_ clings to the Aldera database, licking its paw, reaching for the network. _‘You have your_ ridiculously overpowered _computer on the way, why can’t you just… let the research wait. Have some patience.’_

 _‘Merone might erase what I need if I wait too long—‘_ Except, Merone has been toying with Hayato’s lack of virtual security for years now, Izuku is pretty sure this is a game for them by now. _‘What if I… try to get through_ uri _, while_ uri _is here already—‘_

Izuku doesn’t know if that experiment worked, but he _does_ know Hayato doesn’t get any sleep for the next week.]

Hayato isn’t made for _waiting_. Most of his plans are time-sensitive of the immediate manner, need to be executed the moment they are made or he stresses about them and explodes: he doesn’t really see the bigger picture, or a longer timespan unless it involves his long term goal of taking over the world. If he is waiting, then he probably _can’t_ do anything just yet, and if the Heroes are here then maybe his plan is already busted.

Whichever it is, Izuku doesn’t trust him, at all.

(That came out wrong. He does trust Hayato, but that’s because Hayato would _never_ hurt him. What he doesn’t trust, is Hayato’s common sense working properly, because Hayato lives in an parallel world of only 5.5 citizens, where the law bends to fit his needs and desires. He probably didn’t think twice about coming here, didn’t even consider that he could be found and labelled a criminal, or that someone else would fix this matter _for_ him.)

“It is the _wrong building_ ,” Hayato finally says after too long of staring at Izuku. He is still vibrating with anxiety, hands clenched tight. He takes out a watch from his pocket just to fiddle with it as he jumps back to his perch on the wall. “Katsuki is elsewhere, so…”

“Wait, you’re saying he is _not here_ —“

If Katsuki isn’t here, and the Heroes are here, then—

“Then, where is he? We should go there, why are we wasting time!?”

“Am just… waiting.”

Izuku has enough sense to pull his friends with him as he drops into the foxhole and, not a second later, the explosions begin.

* * *

Gokudera Hayato dies in a glow of red flames, explosions and a bow in hand. He doesn’t know what happened, how it happened, or who was there. All he knows for a long while is _flames_.

And then a spark of identity comes to life, and Bakugō Hayato is looking up at his crying brother. His head hurts. He remembers— a burning building, and lots of screaming, but he is outside, in a river, and he is bleeding from a head wound that _should_ have killed him.

He has a brother, no, he has a _sister_ , and a family of annoying little siblings, maybe even a daughter—and he is four years old, and fourteen, and twenty-four and thirty-two and he knows so much yet so little—

Dying Will Flames truly are amazing phenomena.

Hayato, the sequel, is the youngest twin of the Bakugō couple ( _Bakugō_ as ‘powerful bomb’, _Hayato_ as ‘way of the arrow’, it is hilarious in how accurate it is), a model-and-designer couple living in Musutafu, Japan. His older brother is Katsuki, who can make his hands explode and spends all of Hayato’s short hospitalization hovering and reading out loud. The nurse asks some questions and he replies automatically: his name, his age, what year is it, what is his Quirk.

The year is 22XX A.D., and he is _so confused_. What is a Quirk? Hayato _knows_ , because he grew up in this time. The scattered memories of his previous incarnation aren’t enough to put together a whole picture, but they are enough to confuse him a lot, and also why is he always the _youngest_ brother?

At least Katsuki is not as crazy as Bianchi.

Gokudera Hayato’s memories are not enough to make Bakugō Hayato’s life worse than it should be, though. He does not remember much, only some people, some names, _Tsuna_ , his flames. It is weird to not have them flaring behind his eyelids, but he supposes he hasn’t trained his body for them so he _shouldn’t_ have them, but it is also weird he hasn’t awoken his Quirk so maybe he is just too weak?

No, he won’t consider that.

Hayato decides he needs answers, so he resorts to his favorite pastime: knowledge hoarding.

[ _1\. At least two centuries in the future; Quirks, mutation of Flames, evolution? Another dimension maybe? Has been too long, cannot know._

_2\. No records of Gokudera, not unexpected; Namimori database is off limits. Namimori is now ‘Quirkless Autonomous Region’, weird as hell._

_3\. Vongola? No idea, organized crime ‘downfall’ was a century ago. Information hard to come by. There are Villains now? And Heroes?_

_4\. Check the time capsule._ ]

He manages to put together a general picture of things within a few years. Finding information is _really_ hard as a civilian, and as a child, and he doesn’t have resources to _do_ anything. But, the scraps of information he _can_ access help his previous memories become clearer, so it is something.

The first time he tries to get into the Vongola database, he fries his father’s computer and gets locked out of the office. When he wants to borrow a book, he needs a library card, and for that he needs an adult. His parents have already figured out he is obsessing, so they establish new rules, and by then Hayato is already old enough to realize he needs to be discreet.

Hayato was never good at being discreet. Luckily for him, he has a genius brother and an equally obsessive childhood friend, so he doesn’t _need_ discretion: he can misdirect, and neither Katsuki or Izuku mind the attention.

(Katsuki doesn’t really approve of his research, but supports him anyways. Well, that’s fine, Hayato doesn’t approve of his _Hero_ thing either, but he will support his brother always.)

As for resources… Well, he is _Vongola_.

Time travel is in their blood.

He _is_ still surprised the time capsules have survived two centuries, the fall of an empire and the destruction of a whole city, but Merone was built to withstand a _nuclear war_. It is just a safety measure, Tsuna said, we won’t need it, it doesn’t _need_ to be so strong. I would feel better if it existed, Byakuran argued, I don’t want anything like that event to happen again, please, just do it.

He is even more surprised one of his old mail addresses is _still_ viable. Maybe not all hope is lost for Vongola.

So, he goes in.

> [ **New!** To: _gh.arcida59@nmmr.vgl_
> 
> From: _stormbearers@axis.tns_
> 
> Subject: _aptljhwzbsl_
> 
> > tc.tns/obyypjhul/
> 
> > welcome back]

Hayato almost cries when a random virus kicks him out. The last time it was active was just _yesterday_ , that means there is someone else running around in the wrong century just like him. Of course, he can’t tell who it is —the capsule is completely automated and it is made to be completely untraceable, he doesn’t know how it works, but it _works_ , and he _isn’t alone_.

He can relax for a bit. Only a bit. Maybe a week.

And then he wakes up to a cloyingly sweet smell in the room and Katsuki looking at him from the open door.

Ah, yes. His Quirk.

He is ten (he thinks, he feels so old), when it manifests. One part acetone, one part hydrogen peroxide, put them together and it _explodes_. Add in Katsuki and it explodes _even more_. It is beautiful, he loves it, but also, he hates it _so much_.

Because now he can’t feel his Flames. At all. Before the Quirk showed up, they were weak, barely flickering and struggling to stay aware, but _there_ , bright Storm red with wisps of other colors. Now? They are— _colorless_.

Not white, not black; not Oath or Night. Just _colorless_. Unaligned, like they don’t quite know where to go, or what to do. A will without aim. A Storm without Sky.

Hayato doesn’t know what’s wrong with him.

But, well, _nothing_ is wrong with him, not physically. If he hadn’t thought Quirks were a sick manifestation of Flames twisted by _something_ , then he would think so now. He would _know_ so now, and the proof is right before his eyes. Right in Hayato’s own colorless soul that would take _years_ to go back to red, or Katsuki’s faded will smothered under his explosions, or Izuku’s crackling lightning that shone in his eyes when he had a mystery in front of him.

[ _‘Anything that changes the alignment of the Flame should be feared,’_ Uni tells them, quietly closing the door behind her, hiding Bykauran’s fading form from their eyes. It is the fourth month, and time has run out. _‘This illness… We can’t do anything about it.’_

 _‘But— We all have it.’_ Lambo is crying. Hayato hasn’t seen Lambo cry in years. _‘Are we—‘_

 _‘Maybe it is the end of an era.’_ Kawahira has long abandoned them, the last of the divine walking this Earth. _‘The end of the Era di Fiamma.’_ ]

For now, though… He has to fix this mess the underworld of Japan got itself into.

**Author's Note:**

>  **On the Twins and Izuku:** Because Hayato grew up quirkless for a long while, Katsuki can’t insult Izuku without insulting him either. They are friends and really protective of each other. They both know Hayato has some shady goals and does Stuff in his spare time, but what can you do; Katsuki is more aware of how deep Hayato’s shady businesses go than Izuku, but Izuku is more up-to-date with the Vigilante nonsense. Also Izuku is a Lightning, Katsuki is supposed to be a Sky, no I don’t care Izuku is the protagonist.
> 
>  **Time capsule?:** The Vongola and affiliated families tends to have time travel incidents, so they made it easier for misplaced people to find resources and information through use of codes, secure online servers and annoying mail addresses. It is managed at the Merone Base in Namimori, so it survived the 2 centuries between canon KHR and the BNHA time.
> 
>  **Where is everyone?:** The others are around! They have their own situations, and they are all amusing to me. Hibari is in Namimori, obviously, Ryohei, Kyoko and Hana are near him. Mukuro is experienced with reincarnation so he just continued his old life where he left it and is the most knowledgeable of what’s going on, while Chrome pretends she is a Normal Civilian Going to School with Tsuna. Tsuna himself is in a sticky situation while the other Tri-ni-Sette Skies and Earth are having the time of their lives. Lambo and Takeshi are the two who went into heroics proper, Lambo because his family pushed him into it because his Quirk is amazing for rescue work (he hates it), and Takeshi accidentally signed up for UA entrance exams and decided to stay because it is hilarious (especially considering who his family _are_ ), but then he got kidnapped by the League so, uh.


End file.
